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In-Reply-To: <d3626070-96d4-4c9d-a866-0345f6ed1205@www.fastmail.com>
Reply-To: Levi Morrison <levi.morrison@datadoghq.com>
Date: Tue, 28 Apr 2020 19:19:58 -0600
Message-ID: <CAAKU0ukx8RZ3RN0br__rKdj7WiAaLC6eSLABt+bu0SkWD5+yXA@mail.gmail.com>
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [VOTE] match expression
From: internals@lists.php.net ("Levi Morrison via internals")

On Tue, Apr 28, 2020 at 6:58 PM Larry Garfield <larry@garfieldtech.com> wro=
te:
>
> On Tue, Apr 28, 2020, at 7:37 PM, Levi Morrison via internals wrote:
> > > One issue that was discussed a few weeks ago, and led to the current =
syntax, was too many variations within the switch syntax; of course, trying=
 to do it all in one syntax is perpetuating that problem.  However, I think=
 Rowan has suggested a syntax that may be sufficiently self-documenting.  T=
o wit, independent of rustmatch (above):
> > >
> > > switch ($foo) {
> > >   case 1: {
> > >     Many statements here.
> > >   }
> > >   case 2: {
> > >     Many statements here.
> > >   }
> > > }
> > >
> > > The curly braces are already understood by most PHPers to mean "a blo=
ck of statements", and so it's a logical jump in this case.  As Rowan sugge=
sts, the {} imply a break.  To keep it simple we should probably not allow =
mixing and matching in a single switch.  Either list-style (break required)=
 or {}-style (break implied).
> > >
> > > That handles break;
> >
> > Sadly, it doesn't. That code is valid today:
> >
> >     <?php
> >     $foo =3D 1;
> >     switch ($foo) {
> >         case 1: {
> >             echo "1\n";
> >         }
> >         case 2: {
> >             echo "2\n";
> >         }
> >     }
> >     ?>
> >
> > Which outputs:
> > 1
> > 2
>
> ... Well, crap.  It just can't be easy, can it...
>
> Would it be too context-sensitive to have the {} version only work in str=
ict switch?
>
> Or for that matter... is anyone actually using that syntax in the wild, o=
r is it hypothetical?  Viz, if the behavior of that changed in 8.0 (a major=
 release), would that even break anything?  Even 7.4 has a couple of "the b=
ehavior changed but seriously who was using this anyway?" points in it.  Co=
uld we get away with just changing it for 8.0?
>
> I'm not sure if Nikita's "check the top 1000" script could handle somethi=
ng that subtle.
>
> --Larry Garfield
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php


I am confident it was used in a former employer's codebase, which is
how I immediately knew it was valid. My memory is too fuzzy to
remember anything more than it was used, unfortunately.